# -*- mode: snippet -*-
# name: plyr ddply-summarize Split Data Frame, Apply Function, And Return Results
# key: ddsum@plyr
# key: plyr.ddsum
# contributor: Shuguang Sun
# --
summary.$1 <- plyr::ddply(.data = $1,
                    .variables = c($2),
                    .fun = summarize,
                    ${3: mean = mean(y)}$0)
